Rebound walls are today used for training and practicing a wide range of ball games. Soccer (European football) will hereafter be used as an example of an application. A person skilled in the art would be able to see potential use for other ball games.
A ball rebound device with only one tension setting may be acceptable for practice by users at one level of skill, but wholly unacceptable for practice by others of substantially different skills. For example, a rebound device that has a loose, nonadjustable return tension level appropriately set for a beginning or child player would most likely be unacceptable to skilled players. On the other hand, a ball rebound device that has a tight nonadjustable return tension level appropriate for practice by a skilled player may prove too dangerous for use by a child or a beginner. An inexperienced ball player can easily be hurt by a fast returning ball, particularly if the user is standing too close to the ball rebound device.
An optimal rebound wall is a wall that can be used by both beginners and experienced persons and for training of various skills. There is therefore a need for a wall which can relatively easily be adjusted to the desired application.
There exists today a number of different rebound devices consisting of a metal or plastic frame with a net material lashed to the frame structure. U.S. Pat. No. 5,857,679 discloses such a rebound net using a tension adjustable elastic net material lashed to a frame structure. Adjusting the tension of the elastic netting material allows the user to alter the return speed of a ball hit against the rebound net. The frame structure can be supported with variable tilting. The net is tied with elastics or in elastically adjustable cord spirally wound around the edge of the elastic net and the frame structure. By tightening or loosing the cord, the rebound force is increased or decreased respectively.
U.S. Pat. No. 6,209,877 discloses a rebound device comprising an outer frame fitted with an inner frame. The inner frame consists of four frame parts individually bolted to the inside of the outer frame. The inner frame is provided with through-holes from the inside to the outside of the frame. Through these holes are led one string horizontally back and forth and one string vertically up and down. The two strings are weaved across each other in the same way as we know it from a stringed tennis racket. The tensions of the device increases by tightening the bolts whereby the inner frame parts are pulled closer to the inside of the outer frame and similarly is the tension of the device decreased by slackening the bolts whereby the inner frame moves away from the inside of the outer frame, thereby creating a space between the outer frame and the inner frame.
U.S. Pat. No. 4,489,941 discloses another rebound device with a net and a frame. The frame includes inner frame members. The inner frame has two adjusting rods each attached by spring elements to a side of the netting. The outer frame is attached by spring elements to the two other sides of the netting material. Adjustable screws attach each adjusting rod to outer frame.
The above-described rebound devices suffer from the disadvantages that a ball which hits the frame will achieve a significantly reduced rebound compared to a ball which hits the strings. Furthermore, the ball contact with the frame will result in an unforeseeable rebound.
The applicability of the device for training of ballgames where delivery along the ground is important, such as in soccer (European football) will be reduced. Instead of jumping back with good speed along the ground, a ball which hits the frame will jump both up and back with reduced force.
A further disadvantage of the above devices is that replacing the net is not user-friendly at all.